Different wireless communication systems are emerging based on global communication systems such as those based on satellites; national, cellular communication systems such as those based on GSM; and local wireless networks such as those based on 802.11-type technologies. Most of those networks are based on cells that are served through base stations or satellites, and most networks have built-in capabilities for communication devices to locate the nearest base station, and for hand-overs between adjacent cells within a network as the communication device is moved physically from one cell into another. This is referred to as “horizontal hand-overs”. The described communication systems essentially differ in the size of their individual cells, the size of the entire network provided through the union of those cells, the characteristics of the communication links they provide, and to the degree to which horizontal hand-overs and other management functions are performed automatically or manually. In general, the larger the network the lower the provided communication bandwidth is, the higher the network delays and the higher the costs are.
Hilmat Schmundt in “Mit Superhandy ins Turbonetz”, accessed Jul. 7, 2002 and retrieved from the Internet http://spiegel.de/spiegel/0,1518,druck-201029,00.html points out a need for a cellular phone that has access units both for GSM networks and for W-LAN networks.
Today, cell phones or data networking cards with hybrid GSM/802.11 network interfaces are available. The user can chose by manually activating a switch, which network to use for dialing in. For example, one such card is described on the Internet-Page http://www.nokia.com/phones/nokiad211/index.html, retrieved Nov. 18, 2002.
WO 01/22662 A1 discloses a dual mode subscriber unit for short range, high rate and long range, lower rate data communications. The low-range, high speed wireless communication path is a wireless LAN connection such as an IEEE 802.11-compliant wireless LAN and the long-range, low-speed wireless communication mode is a cellular CDMA-type connection. The communication unit is supposed to connect IEEE 802.11 W-LAN whenever possible. Determining whether the IEEE 802.11 mode is available is achieved by having the communication unit detect a beacon signal, or by having the communication unit transmit a probe request message and detect a probe response message in response to the probe request, indicating the presence or availability of the short-range, high-speed wireless communication path. Alternatively, the availability of short-range, high-speed wireless communication path can be detected by having the communication device detect activity on it.
Having the communication device determine which network to connect to by actively scanning available networks and searching for beacon signals or other network indicating signals is detrimental with regard to consumption of communication bandwidth and with regard to consumption of power.
It would therefore be desirable to provide a more intelligent selection of network resources for establishing a channel for wireless communication.